Another Look At Epoxy Thermosets Correlating Structure With Mechanical Properties

Document Type

Article

Publication Date

9-1-2014

School

Polymer Science and Engineering

Abstract

All glassy epoxy polymers develop macroscopic properties at some degree of conversion. Our selected example, diglycidyl ether bisphenol-A epoxy pre-polymer, was cured with 3,3′-diaminodiphenylsulfone at stoichiometric equivalents using a series of cure profiles to produce distinct variation in the degree of epoxy conversion and result in varying network and network connectivity. Activation energy of epoxy-amine reaction in this selected system was ∼61 kJ/mol. The calculated reaction energy barrier was found to vary with the extent of epoxy conversion and is attributed to multimechanistic reactions. Epoxy-amine conversion was tracked in situ via near infrared spectroscopic analysis. A single cure condition (90°C) was selected for experiments focused on preferential linear chain growth and minimal branching and/or crosslinking. The physical properties for matrix materials from samples prepared to varying degrees of conversion were characterized and tested for fracture toughness, tensile, flexural, compression properties, molecular weight between crosslinks/crosslink density, and glass transition temperature(s). An empirical equation was also designed to predict molecular weight between crosslinks based on chemical connectivity and extent of reaction. POLYM. ENG. SCI., 54:1990–2004, 2014. © 2013 Society of Plastics Engineers

Publication Title

Polymer Engineering and Science

Volume

54

Issue

9

First Page

1990

Last Page

2004

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